This invention relates to a flush valve and more specifically to a flush valve for releasing a predetermined volume of liquid upon actuation thereof.
Flush valves are used to release a predetermined volume of liquid from a source of pressurized liquid upon actuation thereof. One common use of flush valves is in connection with plumbing fixtures such as urinals, water closet bowls, mop sinks or the like. The inlet of the flush valve is connected to a water line having pressurized water therein and the outlet is connected to the plumbing fixture. Upon actuation, the flush valve releases a predetermined volume of water into the plumbing fixture.
When a flush valve is in a normally closed position, it is desirable to block the flow of the pressurized liquid in the inlet from both the outlet and the internal operating components of the valve. U.S. Pat. Nos. 3,008,682, 3,008,683, 3,279,742 and 3,399,860 disclose flush valves of various constructions which depend for their operation on the pressurized liquid from the inlet to be conducted through various passages in the internal working components of the valve and contained in various chambers in the valve with various sealing devices when the valve is in the closed position. Consequently, these internal working components of the valve are constantly exposed to the pressurized liquid from the inlet. Various points of leakage of the pressurized liquid, both internal and external, may occur when the internal working components of the valve are exposed to the pressurized liquid and the valve is in the closed position. It is desirable to isolate the points of leakage in a flush valve to minimize replacement costs and repair problems.
Each of these references also require that the chamber between the piston and the housing be capable of maintaining pressurized liquid therein so that the valve will move from an open to a closed position. If leakage, either internal or external, from this chamber occurs, the operation of the valve will be impaired or even inoperative depending on the amount of leakage.
Since these flush valve designs require pressurized liquid in certain of their operative chambers and passageways, and depend for their operation on pressurized liquid in the various chambers and passageways of their working components, if the liquid pressure at the inlet is lost or becomes a negative pressure the operation of the valve is impaired even after a positive liquid pressure is restored at the inlet. Generally, a check valve or a stop valve is used in the conduit supplying pressurized liquid to the inlet of these flush valves. The stop valve operates to close the liquid supply conduit leading to the inlet of these flush valves when pressure in the line is lost and reconnect the liquid supply conduit when pressure is restored in the line. Such stop valves are used in an attempt to keep liquid in the operational chambers and passageways of these flush valves so that they will be operative when liquid pressure is restored.
It is desirable to adjust the predetermined volume of liquid released by a flush valve. Such an adjustable flush valve may be used in the installation of different plumbing fixtures since different fixtures require different volumes of liquid. An adjustable flush valve may also be used to compensate for the particular liquid source pressure and flow rate of the liquid supplied to the flush valve at any particular installation site. The pressure and flow rate of the liquid supplied to the flush valve are dependent on a number of varying factors, for example, the pressure on the liquid at its origin, the size of the transporting pipes and the height of the installation.
Several flush valves which provide for adjusting the predetermined volume of liquid released are known. The flush valves disclosed in Filliung et al, U.S. Pat. No. 3,008,682 and Filliung et al, U.S. Pat. No. 3,008,683 provide for adjusting the volume of liquid released by means of an adjustable mechanical stop which adjustably limits the movement of the piston. The use of restriction rings to adjust the amount of liquid released by a flush valve is disclosed in Billeter et al, U.S. Pat. No. 3,399,860 but this flush valve construction requires disassembly of the valve to change the restricting rings.
It is also desirable to limit the volume of liquid released by a flush valve to the predetermined amount even if the valve remains in an actuated position. Such a volume limiting feature operates to save the use of unnecessary amounts of liquid.
Various designs have attempted to provide for limiting the volume of liquid released by a flush valve to the predetermined amount even if the valve remains in an actuated position as disclosed in U.S. Pat. Nos. 3,008,682, 3,008,683, 3,279,742 and 3,399,860. Each of these designs depend on the maintenance of a smooth sliding relationship of various parts of the valve and that gravitational forces will be sufficient to return the volume limiting device to the operating actuatable condition.
It is desirable that a flush valve be constructed to decrease the size, weight and cost of its manufacture. It is also desirable to provide a flush valve having decreased sensitivity to variations and fluctuations in the liquid pressure supplied to the inlet of the valve. Another desirable feature is a flush valve capable of operating with a liquid having small particles therein.